Page 52 - JSOM Spring 2021

The true incidence of tension pneumothorax in the prehos- heart rate. Subjective clinical findings were those that can vary
pital setting remains unclear; however, current literature in- between providers. These were findings suspicious for ten-
dicates it is likely low. According to one series by Eckstein sion physiology, such as clinician-perceived decreased/ absent
and Suyehara, who examined civilian trauma patients who breath sounds, tachypnea/subjective shortness of breath or
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underwent prehospital ND, only 5% of patients demonstrated impending doom, rib fractures with chest wall crepitus, flail
objective evidence of improvement in vital signs, and 7% had segment, subcutaneous emphysema, hyperresonance to per-
improvement in subjective symptoms. This brings into ques- cussion, and asymmetry of chest wall.
tion how many of these patients had a tension pneumothorax
as a result of their injuries. A separate study cites a wide range Specific outcomes included the following: (1) improvement
in the incidence of tension pneumothorax, from 0.2% of all in vital signs: diminished tachycardia (heart rate decreased
advanced paramedic life support responses to 1.7% of major to <100 or >10 bpm from baseline), improved bradycardia
trauma patients with an Injury Severity Score (ISS) of at least (defined as a heart rate >50 bpm), improved systolic blood
15. Given this relatively low incidence and the concern for pressure >90mmHg (if <90mmHg at baseline), or Sao >90%
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potential complications from prehospital ND, previous gener- (if <90% at baseline); (2) improvement in subjective patient
ations of surgeons have argued that field personnel should not assessment: decreased shortness of breath or improvement
perform the procedure because the potential benefit is minimal in tachypnea; and (3) improvement in physical examination
and risk of injury is high. 18–20 findings: release of air or blood upon catheter placement, de-
creased asymmetry of the chest wall, improved lung compli-
The purpose of our study was to determine whether prehospi- ance, decreased cyanosis, and/or improved breath sounds.
tal ND is beneficial in the civilian trauma setting and whether
it should be routinely performed by EMS personnel, particu- Statistical Analysis
larly in the critically ill who require extended transportation Chi-square analysis and Fisher’s exact test were used to com-
times by helicopter. Our specific aim was to identify objec- pare proportions among variables, and an unpaired Student’s
tive evidence of ND success based on patient symptomatology t-test or single variable analysis of variance was used to com-
and physiology, and to determine whether technical success pare continuous data. Results were reported as mean ± stan-
of ND depends on the equipment (i.e., diameter and length of dard deviation or median ± interquartile range. We considered
the catheter) or performing provider (i.e., registered nurse or p values <.05 to be statistically significant. Analysis was per-
paramedic). formed using SAS Studio Software for Windows, version 3.6
and R version 3.5.1.
Methods
Results
After internal review board approval, a retrospective review
of prehospital ND data (n = 143 patients, 172 NDs) were ac- Study Population
quired from Air Evac Lifeteam, a single air ambulance service The demographic profile of the study cohort is depicted in Ta-
based out of the Midwest and Southeastern United States serv- ble 1. There were 143 patients in total. The patient population
ing 79 trauma centers in 12 states (AR, AL, MO, WV, TX, IL, was predominantly male (107; 74.8%), middle aged (age =
IN, OK, OH, MS, KY, TN). Records for all transport flights 44 ± 19.2 years), with most having experienced blunt injuries
from January 2011 to November 2011 were reviewed. The (127; 88.8%). In these patients, 172 attempts at ND were per-
prehospital record was used to abstract demographic data, formed. A notable proportion of prehospital NDs were per-
resuscitation profiles, and clinical outcomes. Variables ob- formed at the scene (103/172 attempts; 59.9%). Twenty-nine
tained included patient age, weight, gender, receiving facility, repeat NDs were performed, 11 for misplaced right-sided cath-
mechanism, intubation, vital signs before ND, vital signs after eters, 11 for misplaced left-sided catheters, and 7 for misplaced
ND, laterality, need for bilateral and/or repeat decompression, catheters during bilateral placement. A total of 129 providers
physical examination and physiologic response to ND, ND performed NDs, stratified equally based on background (79
catheter characteristics, patient mode of transportation, mech- registered nurses vs. 97 paramedics). The success rate of ND, as
anism of ND failure if known, and provider training back- determined by prespecified, clinically relevant cutoffs and defi-
ground (i.e., registered nurse vs. paramedic). nitions of clinical success on examination, was 80.2% overall.
Patients were then stratified based on prehospital patient The distribution of indications for prehospital ND is depicted
characteristics and the following indications for ND based on in Table 2, which shows the distribution of reasons why pre-
the strength of the indication and the likelihood of tension hospital personnel performed ND. The data indicate that most
physiology. Tension physiology was defined using parameters patients underwent ND because of the classic features of pneu-
similar to those used by various other groups 14,15 : (1) cardio- mothorax (e.g., diminished breath sounds), which may or may
pulmonary arrest; (2) hemodynamic compromise (sponta- not have manifested with tension physiology. Of note, clinical
neous bacterial peritonitis <90mmHg and/or heart rate >120 examination findings linked to respiratory pathophysiology
or <50 beats per minute [bpm] and/or narrowed pulse pres- were the No. 1 and No. 2 reasons most reported by prehospi-
sure <20mmHg); (3) acute hypoxia (oxygen dissolved in blood tal personnel, closely followed by hemodynamic compromise.
plasma [Po ] <60mmHg and/or oxygen saturation [Sao ]
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<90%); (4) combined objective findings (cardiopulmonary The clinical observations by prehospital providers post-ND
arrest and/or hemodynamic compromise and/or hypoxia); are depicted in Table 3. After ND, patients were noted to have
(5) subjective findings only based on patient symptomatology significant improvement in pulmonary pathophysiology more
and/or provider assessment; and (6) combined objective and than any other findings. A rush of air or blood coincided with
subjective findings. This study defined objective findings as improvements in oxygen saturation, improvement of breath
those with absolute values, such as blood pressure, Sao , and sounds, and improvements in respirations.
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50 | JSOM Volume 21, Edition 1 / Spring 2021